In flat panel displays (FPDs), Thin Film Transistor Liquid Crystal Display (briefly, TFT-LCD) are characterized in small volumes, low power consumption, relatively low production cost, and non-radiations, and thus predominates in the current FPD market.
Currently, the primary structure of TFT-LCD comprises an array substrate and a color filter substrate (CF) assembled together. Among others, the color filter substrate comprises primarily a glass substrate, a Black Matrix (briefly, BM), a color photoresist, and an Overcoat (briefly, OC) layer. In general, BM is arranged between the color patterns formed from the color photoresist in pattern of grids, stripes, or patches, and serves primarily to improve the frame contrast by inhibiting the mixing of various colors. BM can also block scattered light so as to prevent TFT abnormal operation caused by inter-pixel light leakage. The color photoresist comprises red (R), green (G), and blue (B) color layers. For ensuring color uniformity of the color filter substrate and preventing light leakage, there are overlapping regions having a certain width between the R, G, B color photoresists and BMs, and such width is generally more than 3 microns. Moreover, the heights of the R, G, B color photoresists within the overlapping regions are relatively higher than other regions, thereby generating a relatively large height difference. For eliminating such height difference, it is required to apply an layer of OC material to the surface of the R, G, B photoresist to ensure the surface flatness of CF, thereby ensuring the uniformity of rubbing of alignment layer and achieving a high-quality frame. Moreover, the OC layer can also serve as a protective layer to prevent micro-molecule species in the color layer from migrating into and contaminating the liquid crystal layer to cause an unevenness of color. Thus, the flatness and completeness of the surface of the OC layer is essential to improving the quality of the TFT-LCD products. For avoiding the defect of OC layer, the prior art process needs a repair procedure after the formation of the OC layer. Such procedure can repair the OC layer via finishing repair. However, there is not yet effective repair means for addressing the defects caused by the damage of OC layer.